Switchboard connecting-cord and the like.



PrP. CRAVN.

swlTcHBeARD CONNECTING CORD AND THE LIKE.

PHINEHAS PEABSON CRAVEN, OF CHARLTON-ON-MEDLOCK, IVIIAII'CHIESJ!ER,yENGLAND.

SWITCHBOARD CONNECTING-CORD AND THE LIKE.

Specication of Letters Patent.

Patented Mal. 28, 1916.

Application filed May 7, 1913. Serial No. 766,174.

To all whom it may concern Be it known that I, PHINEHAS PEARsoN CRAVEN,a subject ofthe King of Great Britain, residing at Charlton-on-Medlock,Manchester, England, have invented new and useful Improvements in orConnected with Switchboard Connecting-Cords and the like, of which thefollowing is a specification.

This invention relates to improved modes of supporting and protectingswitchboard connecting cords, and the like.

It is common knowledge that telephone switchboard connecting cords arevery liable to break, more particularly at or about the place where thecord enters the switch-plug, but an absolute break of the cord, thoughvery objectionable as it renders the cord useless and necessitates itbeing repaired, is not the worst feature of frequent breaks, becausebreaks attract notice at once, and can be dealt with. Telephoneswitchboard connector cords mostly consist of two or more strands, eachconsisting of many fine copper wires or strips suitably wrapped toinsulate one strand from another. The cord begins to give way by thebreaking of one or more of these fine copper strips, and the more ofthem break, the less eiliciently the cord acts as a transmitter, causingvarious defects in the telephone service, such as indistinctness ofenunciation, intermittent enunciation, buzzing, or modifications ofthese faults. As the defects develop more or less gradually, there is,in the aggregate, great inconvenience caused both to the staff and tosubscribers by ineiicient service, through what may be called cordfaults, apart from the actual breaking of the cords, and all connectingcords, broadly speaking, go through the varying phases of gradualbreakdown before actually breaking, so that any practical arrangementthat would minimize the number of cord breaks would obviously be ofgreat utility. The breaks are largely caused by the sharp bending of thecords at the part referred to, more particularly when the plug is beingpushed into the jack panel or switchboard.

In order that this invention may be more fully understood I will referto the accompanying drawings, in which- Figure 1 represents a. helicalspring b made from flat tape or ribbon-like metal; Fig. 2 shows ahelical spring c withsiX wires wound side by side, a compound spring,interwound upon the same mandrel;

Fig. 3 shows a helical spring d made from tape or ribbon-like metal,which metal is tapered in width, and the spiral of which varies in pitchor distance between coil and coil; Fig. 4 shows a helical spring e madefrom ribbon-like metal having a clip formed at one end for gripping ontothe switchplug; Fig. 5 is a detail perspective view of the tube for theouter end of the protecting support; and, Fig. 6 is a similar view ofthe clip whichvsecures the protecting member to the plug.

Ordinary helical springs made from wire of circular crossesection, andhelical springs made from wire of rectangular cross-section, surroundingthe cords have been used to prevent or minimize the sudden bend of thecords. It has also been proposed to provide the cord attachment with aprotective tubular extension, formed of a number of thin flexiblestrips, to prevent or minimize the sudden bend of the cords. But Iprefer to use two or more helical springs wound side by side, see c,Fig. 2,-which shows six springs wound side by side. Or a helical springmade from flat tape or lribbon-like vmetal may be used, see b, Fig. 1,.vthus obtaining strength combined with small diameter. The pitch of anyor all helical springs may be varied to give 'an increasing flexibilityto the springs as the distance from the plug increases, by coiling thesprings with comparatively wide pitched spirals close to the plug andsuccessively decreasing the pitch or distance between coil and coil'asthe distance from the plug increases, thev flexibility increasingproportionately to the length of wire or metal required to make anygiven length of spring more or less on the principle of the lever'.v y

A short tubular spring g, Fig. 2, formed from a piece of fiat temperingsteel or other suitable metal, and preferably flanged orI bell-mouthedslightly at one end, mounted on or surrounding the cord, may be pushedinto the openingsin the supporting springs,

see g Fig. 2, at one or both ends until the iange or bell-mouth of thetubular spring g comes into Contact with the ends ofthe supportingsprings, preferably maintaining its position in said supporting springby its own outward spring pressure against the internal surface of the'cord-supporting springs. 'lhe short spring tubes provide smoothsurfacesl for the lcords at this part, and prevent them from coming intocontact with ends of wire, or sharp cut edges of 'metal of which thesupporting springs may be made. 0r I may use a short-piece of ordinarytube flanged in the same way, and forced into or -otherwise fastened inposition.

A device to the plug. This describes what is practically a tubularspring of equal section, gripping'the switch-plug with one part, and theprotective spring or other device with the other part, and though thisform of clip acts when the two parts gripped are of equal diameter, incases where the diameter of the plug and spring vary, the part with thelarger diameter prevents this clip from 4gripping onto the smallerdiameter with suiicient firmness. I may use an alternative form of clipto meet variations in the diameters' of the parts clipped, which may tedescribed as a compound or double clip, see lz, k Figs. l, 2 and 3,connected together by a strip or finger of metal, see z' Figs. l, 2 and3, of one quarter or any desired proportion of the circumference of thesaid tubular clip, thev remaining three quarters, or other desiredproportion ofthe circumference of Vsaid tubular clip, being cut away atthat part, see -L Figs. 1, 2 and 3, thus causing a break ordisconnection to a considerable extent between the two clips k, L thusformed, which clips will then act to grip onto, or, if pressed to andinserted into the openings in the plug' and supporting devicerespectively,

expand against surfaces as required to a great extent independently theone clip of the other, I may use compound clips of this type, one clipof adifl'erent'diameter to thefother'to grip onto, or expand againstsurfaces of different diameters. In all cases described as clipping ontothe-switch-plug, it may also be understood to mean alternatively onto apart of the plug turned down' or made of less diameter (see p, Figs. l,2,

l3 and 4) to such an extent as that the outsidev of the clip, whensprung on, need not be of greater diameter than' the switch-plug a,beyond the parts embraced by the clips, see a and h, Figs. l, 2 and 3.This feature is of great utility, as combined with the springs made ofribbon-like metal it enables switchplugs having these attachments beingall ofsmall diameter at every part, to be used in the most modern closeset jack panel, without any structural. alteration in presentinstallations, and without reducing the diameter of the cords 'atpresent in use. In all v cases described as clipping onto theswitchplug, or the cord protecting device, it may also be understood tomean alternatively, the clip being pressed to, and inserted into theopenings in the switch-plug and cordprcftecting devicesrespectively,`and to maintain their'position firmly by their outwardspring pressure against the metal surrounding the said opening. All thespring clips and the tubular springs may be made from sheet metal foldedl.or formed into shape appropriate fo-r being sprung open or pressed toa less diameter, to meet the case of being sprung onto or inserted-intothe switch-plugs or springs as may be, there being a slight opening inthe case of the tubular spring and in the case of the spring clips, orthe edges of the metal can be sprung apart. For insulating the aforesaiddevices I may cover them with an insulation such as plaitedv braid,knitted or textile fabric with or `without resin or gum, such as shellacor indiarubber', preferably melted or in solution for convenience ofapplication; or I may interpose between the plug and the clip, orbetween the clip and the supporting device resin or gum as aforesaid,and which would harden or set after being applied, with'or without othermaterial, such as glass, emery, or the like, which would form a goodgripping surface. laims: v

1. The combination with a switch-plug and cord connected therewith, of aprote'ctive support for the cord in the form of a helical member madefrom a ribbon-like strip cut from a uniformly thick sheet of resilientmaterial adapted to inclose the cord, the said member being of uniformdiameter and having its convolutions decreasing in pitch in directproportion to the increase in distance from the plug, and means forconnecting the plug detachably with the adjacent end of the helicalmember.

2. The combination with a switch-plug and cord` connected therewith, ofa protecvtivesupport for the cord in the form of a helical member ofresilient material adapted to inclose a portion of the cord, means for iconnecting the plug detachably with the adjacent end of the helicalmember, and a protecting tube engaged within the opposite end of thehelical member and having its outer end flared to afford a bell-mouth.

3. The combination with a switch-plug and cor-d connected therewith, ofa protective support for the cord in the form of a helical member ofresilient material and adapted to inclose a portion of the cord, meansfor connecting the plug detachably with the adjacent end ofthe helicalmember. and an expansible'protecting tube of resilient material adaptedto be wedged into the free end of the helical member andrhaving itsouter end flared to aord a bellmouth. v Y

4. The combination with a switch-plug and cord connectedV therewith, ofa protective support for the cord in the form of a helical member madefrom a ribbon-like strip cut from a uniformly thick sheet of resilientmaterial, the said member being of uniform diameter andhaving itsconvolutions decreasing in pitch in direct proportion to the increase indistance from the plug, and means' for connecting the plug detachablywith the adjacent end of the helical member,.the strip forming thehelical member being -tapered to decrease in axial width away from theplug.

'5. The combination w1th a switch plug and cord connected therewith, ofa protective support for the cord in the form of a helical member madefrom a ribbon-like strip cut from@ uniformly thick sheet of resilientmaterial and arranged to inclose the cord adjacent to the plug, andmeans for connecting the plug detachably with the adjacent end of thehelical member, the strip forming sald member being tapered to dg.-

, crease in axial width yaway from the plug.

6. The combination with a switch-plug and cord connected therewith, of aprotective support adapted lto inclose the cord adjacent to the plug,and being inthe form of a helical member of resilient material, and alongitudinally split. tubiform clip of resilient material adapted togrip terminally the plug and helical member to connect the Same. I

7 The combination'with a Switch-plug I and cord connected therewith, ofa protective support adapted to inclose the cord adjacent tothe plug andbeing in the form of a helical member of resilient material, and alongitudinally split tubiform, compound clip of resilient materialadapted to grip` terminally the plug and helical member to connect thesame, the said clip being -provided medially with an arcuate slot eX-tending oppositely from tle longitudinal edges of the VYsame.l i

8. Switch-plug connected cord protecting support comprising incombination, a Ahelical spring lmade from a strip of ribbon-like metaltapered in width, said spring having a relativelywide pitch near itsconnection to the plug and decreasing in proportion to the increase ofdistance from said plug, a

cord protecting tube withV a bell-mouth in-v serted in one end of theprotecting support and a compound tubular .clip mounted on the other endthereof, said clip forming a.

